Seismic
surveys first came on the scene in the 1980s. Companies in the petroleum industry use seismic technology to locate oil and natural gas deposits. Seismic
exploration involves mapping the sub-surface geology using sound waves generated
from special equipment. This equipment, usually mounted on trucks, is carried
across the landscape along straight lines and readings are taken at measured
intervals. Often a series of parallel lines of vegetation is cleared to allow
seismic exploration, leaving long, narrow cutlines, called seismic lines. These
lines are often maintained for many years for further seismic exploration or
general access by other forest users, but eventually they are reclaimed or
naturally reforested.

Every
year, a great deal of seismic activity occurs throughout Alberta, on both public
and private lands. The amount of seismic activity varies greatly from year to
year, depending on the energy market and other factors. During the early 1990s,
341,288 kilometres were covered by seismic exploration. Just over two-thirds
(67.2 percent) of this activity occurred in the settled part of the
province.

Exploration
companies often take advantage of existing cutlines for their seismic activity.
During the 19901994 period, about 45 percent of the exploration on public lands
used existing cutlines. Although this reduces the number of new seismic lines
that must be cut, it delays the eventual reforestation of existing lines as they
continue to be used.

Department of the Environment. State of the Environment Report, Terrestrial Ecosystems. Edmonton: n.p., 2001. With permission from Alberta Environment.